摘要
Ionic thermally activated delayed fluorescence(TADF)emitters are rarely investigated due to their poor photoluminescence and electroluminescence performance.Herein,highly efficient ionic TADF emitters with charged donor–acceptor(D–A^(+))and D–A^(+)–D architectures are designed,innovatively based on the phosphonium cation electron acceptor.The symmetric D–A^(+)–D compound in doped film exhibits a high photoluminescence quantum yield of 0.91 and a short emission lifetime of 1.43 microseconds.Partially solution-processed organic lightemitting diodes based on these ionic TADF emitters achieve a maximum external quantum efficiency(EQE)of 18.3%and a peak luminance of 14,532 candelas per square meter(cd/m^(2))and show a small efficiency roll-off of 7.1%(EQE=17%)at a practical high luminance of 1000 cd/m^(2).These results demonstrate the high potential of phosphonium cations as promising electron acceptors to construct TADF emitters for high-performance electroluminescence devices.The current study opens up an appealing way for future exploitation of high-efficiency ionic TADF materials.
基金
This research was made possible as a result of a generous grant from the Key Research Program of Frontier Science,the Chinese Academy of Sciences(CAS)(grant no.QYZDJ-SSW-SLH033)
the National Natural Science Foundation of China(grant no.52073286)
the Natural Science Foundation of Fujian Province(grant no.2006L2005)
the Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China(grant nos.2021ZR132 and 2021ZZ115)
the Youth Innovation Foundation of Xiamen City(grant nos.3502Z20206082 and 3502Z20206083)
the Major Research Project of Xiamen(grant no.3502Z20191015).
